P0734 Code: Gear 4 Incorrect Ratio
🟠 Moderate severity · drivable
Drivable, but fourth gear is slipping, which can cause serious internal damage if ignored.
What P0734 means
The transmission is slipping in fourth gear — the computer commanded fourth gear, but the actual ratio didn't match. A slip limited to fourth gear points to the clutch pack or band that engages fourth gear, or to low/old fluid. If other gears slip too, the cause is more likely systemic (see P0730).
Symptoms
- Check engine light on
- Slipping in fourth gear
- Harsh or delayed shifts
- Reduced acceleration at speed
Common causes
- most common: Low or dirty transmission fluid
- common: Worn fourth-gear clutch pack or band
- less common: Faulty shift solenoid or valve body
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Check and change the transmission fluid and filter | Yes | $100–250 |
| Repair internal transmission slippage | Mechanic | $1500–4000 |
Frequently asked questions
Is a fourth-gear slip serious?
Yes. It usually means a worn clutch pack or band, and driving on it accelerates internal damage.
What if only fourth gear slips?
A slip confined to one gear points to that gear's clutch or band. Slipping in multiple gears suggests a fluid or system-wide problem (P0730).
How much does it cost to fix P0734?
A fluid change is $100–250; a rebuild runs $1,500–4,000.
Related codes
P0730
P0730 Code: Incorrect Gear Ratio
P0733P0733 Code: Gear 3 Incorrect Ratio
P0735P0735 Code: Gear 5 Incorrect Ratio
Related guide: The 10 Most Common Check Engine Codes →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.